如何在注册时将组件实例化为单例？

Question

I can imagine this might be quite straight forward to do in Castle but I'm new to the technology and have been Googling for hours with no luck!

I have the following:

container.Register(
Component.For<MySpecialClass>().UsingFactoryMethod(
    () => new MySpecialClass()).LifeStyle.Singleton);

Now quite rightly this is being lazy-loaded, ie the lambda expression passed in to UsingFactoryMethod() isn't being executed until I actually ask Castle to Resolve me the instance of the class.

But I would like Castle to create the instance as soon as I have registered it. Is this possible?

Answer 1

For this simple case you could just register an existing instance :

var special = new MySpecialClass();
container.Register(Component.For<MySpecialClass>().Instance(special));

Answer 2

You can just use the built it Startable facility like so:

container.AddFacility<StartableFacility>();
container.Register(Component.For<MySpecialClass>().LifeStyle.Singleton.Start());

You can read about it here

Answer 3

The answer re using "Instance" may not always be feasible (if the class has layers of dependencies itself, it won't be easy to new it up). In that case, at least in Windsor 2.5, you could use this:

    public static void ForceCreationOfSingletons(this IWindsorContainer container)
    {
        var singletons =
            container.Kernel.GetAssignableHandlers(typeof (object))
                     .Where(h => h.ComponentModel.LifestyleType == LifestyleType.Singleton);

        foreach (var handler in singletons)
        {
            container.Resolve(handler.ComponentModel.Service);
        }
    }

    // usage container.ForceCreationOfSingletons();